Energy saving undercabinet lighting system using light emitting diodes

ABSTRACT

The present invention relates to an undercabinet lighting system including a low profile switch mode power supply contained in a special electrical junction box and use Light Emitting Diodes with long life. The system is powered by a high energy efficient switch mode power supply with low power consumption. The height if this lighting system is very close to half of one inch or less. The transparent diffuser is positioned over the Light Emitting Diodes for uniform illumination over a desired area. These luminaries can be ganged or linked by direct mating connectors.

BACKGROUND OF THE INVENTION

The present invention is specifically designed for the replacement of Tungsten filament lamp or Compact Fluorescent lamps also known as CFL lamps like one or two F8T5, PL9W or PL13W.

A light-emitting diode (LED) is a semiconductor device that creates light using solid-state electronics. A diode is composed of a layer of electron rich material separated by a layer of electron deficient material which forms a junction. Power applied to this junction excites the electrons in the electron rich material leading to photon emission and the creation of light. Depending on the chemical composition of the semiconductor layers, the color of light emission will vary within the visible range of electromagnetic spectrum.

LED's are much more energy efficient than their incandescent counterparts for several reasons. LED's produce uniform light dispersion and light output is dispersed evenly over the lens which make them brighter than incandescent lamps. LED's are very energy efficient producing up to 90 percent light output with very little heat while incandescent bulbs use up to 90 percent of their energy generating heat. Incandescent lamps only produce white light which must be filtered for traffic signal use, and this leads to an additional loss in energy. LED's, on the other hand, produce colored light that does not need to be filtered out—all of the energy is concentrated around one color band and none is “wasted” on undesired colors.

The benefits of LED lighting technology include features such as energy savings, long service life, high quality light, and cold temperature operation. In addition to these benefits, LED's do not contain any mercury or lead and have no glass to break.

LED's presently use compound semiconductors. The color of the light is determined by the bandgap of the semiconductor. LED's using AlInGaP compound semiconductor alloys can emit in the yellow-red spectrum, while LED's using AlInGaN compound semiconductor alloys can emit in the Ultra Violet—blue-green spectrum. A combination of red, green, and blue LED's, or a blue or UV LED with phosphors can be used to create white light.

The Light Emitting Diode emits electromagnetic wave in the visible spectrum of the electromagnetic spectrum.

The forward voltage and the necessary current are provided by the power supply system. A simple power supply systems provides power for 56 or less Light Emitting Diodes. Typically the LED's are arranged in series and parallel configuration as shown in Fig I and laid out in Printed Wiring Board Fig J. Generally there are 2 types of power supplies, magnetic and electronic switch mode. In this lighting system, the switch mode electronic power supply is used for energy efficiency, low profile, light weight, and a high power factor.

While a preferred embodiment has been shown, modifications and changes may become apparent to those skilled in the art which shall fall within the spirit and scope of this invention. It is intended that such modifications and changes be covered by the attached claims.

LED's do not contain mercury and is environment friendly.

The simplicity of the power supply using very few components greatly improves the reliability of this lighting system.

DESCRIPTION OF EMBODIMENT

In the preferred embodiment, two configurations are described, one with 56 LEDs and another with 80 LEDs. The 56 LEDs put out enough light output to replace an undercabinet light fixture using one F13T5 fluorescent lamp.

The 80 LEDs put out enough light output to replace and undercabinet fixture using one F15T8 fluorescent lamp.

In these embodiments, there is 40% energy savings as compared to the corresponding fluorescent lamps.

The numbers 56 and 80 are arbitrary and so chosen to be cost effective. These numbers could change depending on growth LED technology resulting in cost reduction with higher lumens per watt LEDs.

The design of the power supply is so chosen to put out 42 Vdc maximum and still come under Class 2 requirements of Underwriters Lab standards, UL 1310. Refer to FIG. 6

Transformer T1 shown in FIG. 6, steps down the input high voltage pulses to low voltage pulses.

The diode D7 rated 1 Amp. 400V, rectifies to DC voltage is coupled to resistor RIO rated 5.1 ohms.

The output filter network consists of a resistor R12 rated 10 Ohms coupled to a capacitor C12 rated 680P. Fd., 150V in series coupled to capacitors C8. C6 rated 220M.Fd. 35V to smooth out the ripple voltage. Capacitor C13 rated 104 P.Fd, 50V further smoothes out the output voltage wave shape closer to DC with least amount of ripple. Output choke L1 is coupled between C7 capacitor and diode D7 further stores magnetic energy to provide a constant output voltage.

Resistor R11 and rated 44K ohms. with a series choke L2 and a parallel capacitor rated 470M.Fd.25V forms the output filter network.

There is a feedback circuit consisting of resistor R8 rated 38.3K. Ohms coupled to IC2, TL 431A which is an adjustable reference zener diode. This zener diode is coupled to the power supply through a resistor R10, R11 rated 5.1 K Ohms and 44 K ohms respectively.

The turn on reference voltage is determined by R11 and R10 Ohms coupled to capacitors C6, C8 rated 220 M Fd. 50V.

When the output exceeds the set voltage, the IC2 turns on providing a signal to Opto Isolator U1, model PC817 through U3, the adjustable reference zener diode model TL 431 to the pin 9 of the control IC V2 by charging the capacitor C10 rated 22 P Fd, 50V

Capacitor C9 rated 68 P.Fd. 50V provides the timing frequency for oscillations.

Diode D5 rated, IN 4007 coupled with transformer and capacitor C4 rated 47 M.Fd., 16V provide start up current for the transformer oscillations.

Capacitor C13, rated 10 P.Fd, 50V is coupled to ground to absorb the transient voltages appearing across the output.

Capacitor C7 rated 100 M Fd, 35 V provides necessary filtering of the output voltage to reduce the output ripple

Power Supply:

Refer to FIG. 7

The power supply has an input stage filter network consisting of a metal oxide varistor, RV1 rated 150V for surge suppression, a safety current limiting fuse, F1 rated V2A 250 Vac, and an across the line capacitor C15. rated 22 P.Fd. 250V to absorb the transients.

The second stage is a full wave bridge rectifier consisting of four 1N4007, D1-D4 diodes, rated 1 Amp. 400V with a filter capacitor rated 4.7M.Fd., 400V.

The third stage feeds the rectified AC voltage to an integrated chip IC THX203X which determines the pulse width after converting the rectified voltage to high frequency chopped voltage.

The processed signal is fed to the transformer T1 shown in FIG. 6 made out of ferrite core with the following construction.

Primary Windings:

18 Turns on the magnet core EFD15 from Pin 1 to Pin 3 by 0.15 mm enamel.

Second Windings:

135 Turns on the magnet core EFD15 from Pin 2 to Pin 4 by 0.2 mm enamel. Wind 32T on the magnet core EFD15 from Pin 8 to Pin 5 by 0.2 mm×3 enamel.

DETAILS OF THE DRAWINGS

FIG. 1 shows the front view of the entire LED undercabinet unit Lamp unit.

FIG. 2 shows the front view of a Quick connector for easy electrical connections

FIG. 3 shows the front view array of layout of the LED on a Printed Wiring board

FIGS. 4 and 5 shows the wiring of LED arrays in series parallel circuit

FIG. 6 shows the schematic diagram of the circuit of the LED Power Supply

FIG. 7 shows the circuit diagram of the output transformer of the LED Power Supply 

1) A preferred embodiment of under cabinet lighting system comprising: An isolated power supply circuit electrically coupled to the LED arrays with a means to provide power to the LEDs in such a manner that the system is characterized by a power factor of at least 90%. 2) The lighting system has an array of LEDs connected in series and parallel combination in varying quantity mounted on a printed wiring board as shown in FIG.
 3. 3) An aluminum extruded body serves the purpose of holding LED arrays and power supply in position and provides housing as shown in FIG.
 1. 4) One end cover contains the input male connector for the power supply circuit as marked 8 in FIG.
 1. 5) The other end has a female connector to directly couple another lighting system without additional wiring as marked 5 in FIG.
 1. 6) An energy efficient low profile, typically about 13 mm height power supply marked as 3 FIG. 1 is provided with an integral high power factor circuit to provide the necessary voltage and a predetermined constant current to power the LEDs. 7) A specially angled diffuser marked as 7 in FIG. 1 to provide maximum coverage of the light output from the lighting system over the working area of the undercabinet. 8) The LED arrays as shown in FIG. 3 are so shaped and formed to reduce the light output near the wall and provide more under the cabinet working area. 9) The lenses of LEDs as marked 6 in FIG. 1 are so chosen that the inner array near the wall has 30 degrees spread and the outer array away from the wall has 60 degree spread to achieve more light in the working area of the undercabinet. 10) The integral quick mating male and female connectors make quick electrical connections possible as marked 1 and 5 in FIG. 1 and as shown in FIG.
 2. 11) An integral single pole single throw miniature switch as marked 4 in FIG. 1 serves the purpose of turning the electricity on or off. 12) An electrical surge protection is provided by the power supply by means of a metal oxide varistor as marked Rv 1 in FIG. 7 or transorb or gas filled tube or the combination of metal oxide varistor in parallel with a disc capacitor connected across the input power. 13) An optional dimmer control rotary switch as marked 2 in FIG. 1 is provided to control the LED current for the purpose of dimming. 14) The metal enclosure as marked 1 shown in FIG. 1 not only supports electrical parts but also acts as heat sink with specially designed radiating surfaces with ribs. 